Micro-capsules and micro-encapsulation are terms which are well known per se to a person skilled in the art, which means that there should be needed no definitions of said terms here. It is true that the meaning of the terms "micro" may possibly vary from one application area to another, but since the invention is not directly critical in this aspect, i.e. that a very specific size is necessarily referred to, that term should be considered in the present case merely as the conventionally accepted meaning of particles which are not macro particles of the sizes of several millimeters and thereabove. However, the especially preferable micro-encapsulation technique that is claimed generally gives particles having a size below 1 mm, which means that such particles are generally referred to in connection with the present invention.
Especially within the pharmaceutical and food industries there is today a great interest in encapsulating substances for the purpose of reducing the contacts with the surroundings. There are several known methods of performing a micro-encapsulation, such as e.g. a so-called complex coacervation in an aqueous medium, a phase separation, a polymerization in situ and a coating operation. The protective layer or shell is primarily built up from polymers, synthetic or native ones, or from amorphous lipids. For a survey of these different methods reference is made to Biomedical applications of micro-encapsulation; Lim, Franklin; CRC Press (1984). However, said known methods are connected with disadvantages of different kinds. Thus, it may for instance be that the manufacture is performed in the presence of non-physiological or toxic reagents or that the obtained structure is non-stable or non-reproducible.